Quantitative approaches to research include hard numbers and provable results, such as experiments and surveys. Qualitative research is more subjective, often including observation and interpretation of data via ethnography and personal interviews. Recent approaches to research design include using both qualitative and quantitative research -- a mixed-methodology research design. There are some advantages and disadvantages to this approach.
Exploration vs. Analysis
Most mixed-methodology research begins with a qualitative observation of an event or phenomenon. Qualitative study offers the opportunity to provide subtle details that outline a problem. The research then uses a quantitative tool, like a survey, to validate or invalidate observations made during the qualitative phase. This approach relegates qualitative analysis to an exploratory tool and doesn’t maximize quantitative analysis as a tool to both explore and define a problem and potential solutions.
Broader Perspective
A single-approach design might only include experiments to determine cause and effect regarding a specific issue. Conversely, it might only use observation to tell the story of why a problem has arisen. A mixed-approach design uses the strengths of both methodologies to provide a broader perspective on the overall issue. An experiment may reveal an anomaly that wasn’t evident in observation, while observations provide nuances that can’t be captured in multiple-choice surveys.
Personal Bias
Because people are different, some are more adept at performing one research methodology over the other. A pragmatic person leans more to the definitive answers provided in quantitative research. Those who think in a less linear manner might have a better ability to perform qualitative analysis. If someone leans toward a particular research methodology, the research could suffer from bias unless adjustments are made to account for a methodology isn't a strength for the researcher.
More Data
Mixed-method design expands the research in a way that a single approach can’t. The process of offering a statistical analysis, along with observation, makes the research more comprehensive. Academics glean information from other academics and mixed methodologies offer a broader landscape. There is simply more information from which to develop more hypotheses. Mixed methodology research may advance the timeline of a debate by offering more data for future discussions and research.
Different Answers
Quantitative analysis inherently looks for one answer. When conducting experiments, the goal is to find the one consistent truth throughout the experiment. Qualitative research, however, is inherently focused on multiple answers as interviews reveal a variety of information that may be different, yet true at the same time. Good researchers are aware that this phenomenon could lead to the analysis of different problems at the quantitative and qualitative phases of the research and account for that possibility.